1. Field of the Invention
The present invention is directed to a detector module for use in a computed tomography apparatus, as well as to an overall detector formed from a number of such detector modules, as well as to a method for operating a computed tomography apparatus.
2. Description of the Prior Art
German OS 195 02 574 discloses a detector with a number of parallel detector lines that proceed in the direction of the axis of a subject to be transirradiated, for example of a patient. A plurality of detector lines can be implemented as an assembly unit or a detector module. A sensor array formed of a number of such sensor elements is thereby accepted on a printed circuit board. The printed circuit board is connected via a flexible section to a further printed circuit board on which a plug is mounted for connection to evaluation electronics.
The sensor elements exhibit slightly different properties. It is necessary to calibrate each sensor element in order to avoid image artifacts. Calibration tables can be produced for this purpose with the assistance of special measuring devices. The calibration tables contain, for example, information about the temperature behavior, the radiation drift behavior, the relative signal strength, the afterglow, the location dependency of the signal strength, the spectral behavior or malfunctioning sensor elements.
The production of such calibration tables is extremely time-consuming and cost-intensive. Among the tasks required for this purpose are introduction of the detector modules into a special heating device and to subsequently determining the corresponding calibration data at prescribed temperatures.
Another possibility for avoiding image artifacts to the detector at a constant temperature by means of a heating device. U.S. Pat. No. 5,799,057 discloses a detector wherein the detector housing can be heated with a heating device. The detector housing usually exhibits a temperature elimination characteristic that is not uniform. A constant temperature over all sensor elements thus cannot be guaranteed. Given outage of one or more sensor elements, the entire detector must be replaced.